GB2493697A - Improving traction of vehicle wheels - Google Patents

Abstract

Textile covers have been proposed, for fitment over a tyre to assist with providing grip in snow conditions. An improved device of this type is disclosed, in the form of a tyre cover with a belt adapted to fit around the circumference of a tyre, the belt comprising an inner elastic layer and an outer flexible layer attached to the inner elastic layer at intervals around the circumference of the belt, thus defining a plurality of pockets between the elastic layer and the flexible layer, in combination with a plurality of gripper rods sized to fit within the pockets. The elastic layer is preferably sized to be under tension when fitted to a tyre (or range of tyres) of the size for which it is designed. In other words, the inner circumferential length of the elastic layer should be slightly less than the outer circumferential dimension (when new) of the tyre size (or, all of the tyre sizes in the range) for which the cover is designed. The flexible layer may be may be fixed to the elastic layer directly, or indirectly via a further intermediate layer. It can be of a textile, such as (for example) the textiles recommended in W02000/059745A, or any other material offering suitable grip properties. The gripper rods are ideally resilient, to avoid causing damage to the tyre beneath. They need not be especially hard, in fact, as their purpose is simply to provide a degree of definition to the outer surface of the cover when in use over a soft surface. It may in fact be preferable for them to be relatively soft, as this will improve the ride dramatically when on less compliant surfaces. However, a hard insert may be more suited to severe conditions.

Description

Improving Traction of Vehicle Wheels

FIELD OF THE INVENTION

The present invention relates to the improvement of vehicle wheel traction in low-grip situations. It is particularly applicable during winter snow conditions, but can find application in other low-grip situations such as mud, ice, gravel and the like.

BACKGROUND ART

The annual arrival of snow causes disruption to the transport networks of many countries. Most vehicles are routinely fitted with so-called "summer tyres" which are fully effective at temperatures of about Soc and above and which are able to maintain adequate grip (or traction) with a road surface of tarmac or the like. When the road surface becomes covered with snow, ice, gravel and the like, especially in low temperatures, the tyres are unable to maintain grip and will slip or glide over the road surface. Drivers then find it very difficult to gain momentum from rest, and (if they manage to do so) then find it difficult to exercise adequate control over the vehicle.

This situation is addressed in some countries by requiring the fitment of "winter tyres" during certain periods of the year or climatic conditions. Winter tyres are made of a softer rubber compound that is able to maintain grip on tarmac at lower temperatures, and often have a different tread pattern that can cope with snow and the like. However, it is not practical to use such tyres in all conditions, as they quickly deteriorate when used at high speeds in warm conditions, and often have a maximum speed rating that is significantly less than the maximum speed of modern cars. Thus, winter tyres must be fitted and removed each winter, and stored during the summer months. This is not practical in countries that only experience severe winter conditions briefly or occasionally.

There are, however, a number of countries (such as the United Kingdom) where severe winter conditions are routine, if brief, but not frequent or prolonged enough to justify legislation in favour of winter tyres. In such countries, severe transport disruption during winter weather is common, with vehicles becoming stuck in snow, their drivers unable to return home.

One possible solution is disclosed in WO2000/059745A. This is a textile cover for fitment over a tyre, with an elasticated strap sifting on the rear (inner) face of the tyre to hold the cover in place. A textile surface is then presented on the outer circumferential face of the tyre, which is able to grip in snow conditions. The idea is that the driver can carry a pair of such covers in the vehicle, and fit them if adverse winter conditions are encountered in order to at least complete their journey.

SUMMARY OF THE INVENTION

The present invention seeks to improve upon the device of W02000/059745A.

Whilst better than an un-assisted lyre, this device can meet with difficulty in very soft snow such as that encountered after a recent fall. Generally, in countries such as the UK where there is a tendency to accept that adverse winter weather means travel will be difficult or impossible, it is in the immediate aftermath of a snowfall that drivers particularly need assistance. Whilst useful in snow and (to an extent) ice, the cover disclosed in W02000/059745A is also largely unable to cope with other low-grip situations such as mud or gravel. Further, the simple textile cover of WO2000/059745A does not look sufficiently robust for the purpose, and drivers show some scepticism that it will be of assistance.

The present invention therefore proposes a lyre cover with a belt adapted to fit around the circumference of a tyre, the belt comprising an inner elastic layer and an outer flexible layer attached to the inner elastic layer at intervals around the circumference of the belt, thus defining a plurality of pockets between the elastic layer and the flexible layer, in combination with a plurality of gripper rods sized to fit within the pockets.

The elastic layer is preferably sized to be under tension when fitted to a tyre (or range of tyres) of the size for which it is designed. In other words, the inner circumferential length of the elastic layer should be slightly less than the outer circumferential dimension (when new) of the tyre size (or, all of the tyre sizes in the range) for which the cover is designed.

The flexible layer may be may be fixed to the elastic layer directly, or indirectly via a further intermediate layer or layers. It can be of a textile, such as (for example) the textiles recommended in W02000/059745A, or any other material offering suitable grip properties.

The gripper rods are ideally resilient, to avoid causing damage to the tyre beneath.

They need not be especially hard, in fact, as their purpose is simply to provide a degree of definition to the outer surface of the cover when in use over a soft surface. It may in fact be preferable for them to be relatively soft, as this will improve the ride dramatically when on less compliant surfaces. However, a hard insert may be more suited to severe conditions. Suitable materials therefore include plastics, rubber, metallic materials, such as steel braid or chain, or sections of cord or rope. Ideally, the material will be sufficiently strong to withstand brief use on the road, sufficiently flexible to avoid damaging the tyre, and may be textured or abrasive to assist in providing grip for the tyre.

The attachment of the inner elastic layer and the outer flexible layer can be at varying intervals around the tyre, and in varying patterns. The interval is preferably substantially uniform around the tyre, but can be chosen in order to suit the expected conditions and the nature of the insert. A harder and lower-profile insert might suit a closer interval, whereas higher-profile inserts may suit a longer interval and will preferably be somewhat softer. The pattern can be a simple one, with the inserts held in a pocket that extends perpendicularly across the lyre, or more complex such as pockets that extend diagonally. The latter could serve to reduce the unevenness of the ride resulting from use of the invention.

The pockets can extend across the whole width of the tyre if desired, but need not do so. Indeed, if the pockets are intended only to extend across part of the lyre width then this will assist in designing the same cover to fit a number of different widths of tyre.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the present invention will now be described by way of example, with reference to the accompanying figures in which; Figure 1 shows a view of the inner side of a vehicle wheel fitted with a lyre cover according to the present invention; Figure 2 shows a vertical section through the tyre of figure 1, in the plane of the axle; Figure 3 shows a vertical section through the tyre of figure 1 in the circumferential plane of the tyre; Figure 4 shows an enlarged portion IV of figure 3.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Referring to figure 1, a wheel comprises a hub section 10 including a central hub portion 12 having port holes 14 to allow the wheel to be secured to the vehicle. Spokes 16 extend outwardly from the central hub 12, usually in a decorative manner, to support a dish section 18 that is generally cylindrical in form and extends rearwardly from the spokes 16.

The dish section has suitable lips on its axle inner and outer edges which retain and support a lyre 20. This is then inflated so as to provide a suitable rolling surface for the vehicle in a generally known manner.

According to the invention, the lyre cover is provided having a circular front face (not visible in figure 1) which rests against the outer side of the wheel, i.e. the side which is outermost when fitted to the vehicle. A cylindrical part extends inwardly from the circular section to provide a belt which fits around the outer-circumference of the tyre. A draw cord is provided at the inner extremity of the cylindrical section and may be elasticated, draw-tight, or otherwise securable at a circumference less than that of the wheel so as to pull the lyre cover 22 radially inwardly on a rear face of the wheel as shown in figure 1. A draw-tight cord could be of nylon, steel or other such materials and with a fixing at either end to secure in a loop behind the tyre, retaining the cover in place.

Additional layers within or outside the above-described structure may be provided as necessary, such as to ensure adequate friction with the lyre, or to tighten the cover against the tyre, or otherwise.

Figure 2 shows the lyre cover in more detail, with a front face 24 that is generally circular to approximately match the size of the lyre 20 to which it will be fitted. The cylindrical section 26 extending inwardly from the front section 24 ends (in this example) with an elasticated draw cord 28 that is secured within a pocket 38 that is formed at the free end of the tyre cover. This is sized (when unstretched) to be substantially less than the outer circumference of the tyre so that, when fitted, the lyre cover fits snugly around the lyre 20.

Figure 2 allows the belt section 26 to be seen in more detail. This consists of an outer cover 32 which is integral with and formed by the same material as the front cover 22.

An inner belt 34 is also provided, formed of an elasticated material in the shape of a cylindrical section which, when unstretched, is less or slightly less than the outer circumference of the lyre 20 to which it is intended to be fitted. This means that, when the lyre cover 22 is fitted, the inner belt 34 is in a slightly stretched state, thereby holding it snugly against the tyre 20.

The inner belt 34 and the outer belt 32 are connected together at circumferentially-spaced intervals as shown in figures 3 and 4. These connections 36 can be of any type suited to the materials employed, such as spot welding, stitching, adhesive or the like.

Between pairs of such attachment points, a pocket 38 will be formed as is clearly visible in figures 3 and 4. The dimensions of the inner belt 34 and the outer belt 32 are selected so that the outer belt 32 has a circumference slightly larger than that of the lyre 20 to which it is intended to be fitted. As a result, there will be some slack in the outer cover 32, forming pockets 38. In the configuration shown in figure 3, the joins 36 are arranged so that pockets 38 are formed at circumferential intervals around the tyre cover 22, with regions 40 in between where resilient rods that can be or are inserted into the pockets 38. This could be supplied pre-fitted, or could be provided loose for fitment by the driver. As shown in figure 4, the rods 42 are trapezoidal in cross section but could be any cross section such as circular, square, rectangular, triangular or the like. A flap secured via hook-and-loop fastenings (such as Velcro®) can be provided at one end of the pocket to allow for easy insertion and removal of the inserts while preventing their loss during use.

The figures show the pockets and the inserts to be perpendicular across the width of the tyre. This has the advantage of simplicity and that the cover is laterally symmetrical.

However, the pockets could be formed at a diagonal across the lyre, meaning that the undulation as the vehicle passes over the insert is reduced, or even eliminated if the angle of the insert is sufficient that there is always one between the tyre and the ground. It might then be advisable to supply the covers in a pack of two mirror-image covers so that, when fitted, there is no resultant sideways force.

The result is that, when fitted to a wheel as shown in figure 1, the tyre cover 22 adopts an attitude around the wheel that includes a series of radially projecting bumps 44 around the circumference of the tyre. Each bump provides an additional gripping ability when driving on very soft surfaces. Between the bumps 44, the outer surface of the tyre cover can be of a suitable fabric material to provide the advantages set out in Reference has been made herein to the size of the tyres, but it will be appreciated that tyres commonly are manufactured in a variety of sizes so as to fit different cars. Thus, where reference is made to a size of a tyre it is intended to refer to the size of a specific tyre for which the cover 22 is intended to be fitted, when that lyre is in a new state. Use of the lyre through its design life will result in some wear of the tyre and a reduction in its overall circumference, but this effect is unlikely to have any material effect on the manner in which the invention works. Likewise, one cover 22 may be found suitable for a range of tyre sizes, where these have a circumference and the depth measurement that do not differ substantially so as to exceed the tolerances of the lyre cover.

It will of course be understood that many variations may be made to the above-described embodiment without departing from the scope of the present invention.

Claims (1)

1. <claim-text>CLAIMS1. A tyre cover, having a belt adapted to fit around the circumference of a tyre, the belt comprising an inner elastic layer and an outer flexible layer attached to the inner elastic layer at intervals around the circumference of the belt, thereby defining a plurality of pockets between the elastic layer and the flexible layer, in combination with a plurality of gripper rods sized to fit within the pockets.</claim-text> <claim-text>2. A tyre cover according to claim 1, sized to fit a tyre of a predetermined size, wherein the elastic layer is sized to be under tension when fitted to the tyre.</claim-text> <claim-text>3. A tyre cover according to claim 1, sized to fit a tyre of a predetermined size, wherein the inner circumferential length of the elastic layer is less than the outer circumferential dimension of the tyre.</claim-text> <claim-text>4. A tyre cover according to any one of the preceding claims, wherein the flexible layer is fixed to the elastic layer directly.</claim-text> <claim-text>5. A tyre cover according to any one of claims 1 to 4, wherein the flexible layer is fixed to the elastic layer via one or more further intermediate layer(s).</claim-text> <claim-text>6. A tyre cover according to any one of the preceding claims, wherein the flexible layer is of a textile material.</claim-text> <claim-text>7. A tyre cover according to any one of the preceding claims, wherein the gripper rods are resilient.</claim-text> <claim-text>8. A tyre cover substantially as herein disclosed with reference to and/or as illustrated in the accompanying figures.</claim-text>